The Waste Electrical and Electronic Equipment (WEEE) and Restriction of Hazardous Substances (RoHS) Directives of the European Union were launched to reduce the build up of harmful waste released by electrical and electronic equipment disposed of in landfills.
The concentration of hazardous materials - such as chromium VI, mercury, cadmium, lead, polybrominated biphenyls (PBBs) and polybrominated diphenylethers (PBDEs) - are restricted in electrical and electronic products and/or components.
According to RoHS/WEEE, RoHS limits are applicable to a component if it is possible to mechanically separate it. The definition of what this means exactly is an ongoing process.
It is necessary to reduce these products and components to homogenous, representative samples in order to obtain accurate analytical results.
Traditional grinding methods are not effective for the homogenization of most of the components, including circuit boards, solder, wire, polymers and resins. The simplest method to homogenize these components is cryogenic grinding in the SPEX SamplePrep Freezer/Mill.
Samples are made brittle using cryogenic grinding and can be pulverized through crushing, shearing or impact actions. Even the toughest samples can be ground using this approach.
Analysis of Circuit Boards
Figure 1 shows the analysis of a circuit board. A tiny piece randomly taken from the circuit board would not be representative of the whole board. Sampling and homogenizing many boards ensure that the sample taken for the analysis is representative of the entire batch.
After cutting the sample into manageable pieces, they are loaded into the appropriately sized Chromium-Free Grinding Vial equipped with a magnetically driven Cr-free impactor. The vial is then placed in the Freezer/Mill and submerged in liquid nitrogen until all of the pieces are thoroughly chilled, which typically takes 10 to 15 minutes.
It is possible to chill up to three additional vials in the pre-cool chamber within the mill for high throughput applications. The sample placed in the vial is then pulverized.
Cross-sample contamination can be easily controlled without compromising the sample integrity because the sample is placed separately in a closed grinding vial. Grinding times can differ based on the type of sample analyzed, but the expected grinding time is approximately 10 minutes.
The resulting fine, uniform powder is then used for subsequent analysis, such as XRF and ICP (Figure 1).
Figure 1. Circuit board before and after
6775 Freezer/Mill (Figure 2) is a small cryogenic mill capable of processing samples ranging from 0.1 to 5 g. The mill is equipped with a touch screen that can store up to 20 user-defined grinding programs for easy and quick recall. It also features run history, manuals, training videos and accessories.
Figure 2. The 6775 Freezer/Mill
The specifications of the 6775 Freezer/Mill are given in the following table:
||115 V/60 Hz or 230 V/50 Hz
||19 in (48 cm) x 10.5 in (27 cm) x 12.75 in (32 cm)
||26 lbs (11.8 kg)
||3-prong grounded plug 115 V, 60 Hz. 2-prong European cord for 230 V, 50 Hz
6771 - Small Cr-Free Grinding Vial Set
This Cr-free grinding vial set is suitable for RoHS/WEEE analysis of electronic components for chromium. It comprises of one 6771P small Cr-free steel impactor, one pack of (3) 6751C4 small polycarbonate center cylinders, and two 6771E small Cr-free, ASTM 06 steel end plugs.
6875 Freezer/Mill (Figure 3) is a large cryogenic mill capable of grinding 0.1 to 100 g of the sample. The mill features a touch screen that can save up to 20 user-defined grinding programs in its memory for easy and rapid recall. It also consists of run history, manuals, accessories and training videos.
Figure 3. The 6875 Freezer/Mill
The following table presents the specifications of the 6875 Freezer/Mill:
||115 V/60 Hz or 230 V/50 Hz
||20.5 in (52 cm) x 21.5 in (55 cm) x 18 in (46 cm)
||44 lbs (24 kg)
||3-prong grounded plug, 115 V 60 Hz or 2-prong European plug, 230 V/50 Hz
6883 - Mid-Size Cr-Free Grinding Vial Set
This Cr-free grinding vial set is suitable for grinding electronic components to perform RoHS/WEEE testing for chromium. One grinding vial consists of one 6883P mid-size Cr-free steel impactor, one pack of 6811C4 mid-size polycarbonate center cylinders, and two 6883E mid-size Cr-free steel end plugs. Sample capacity is up to 25 mL (1 - 40 g).
6871 - Large Cr-Free Grinding Vial Set
This Cr-free grinding vial set is ideally suited for grinding electronic components to perform chromium analysis as outlined in RoHS/WEEE directives. It comprises of one 6871P large Cr-free steel impactor, one pack of 6801C4 (3) large polycarbonate center cylinders, and two 6871E large Cr-free steel end plugs.
This information has been sourced, reviewed and adapted from materials provided by SPEX SamplePrep.
For more information on this source, please visit SPEX SamplePrep.